Tribological behavior and wear mechanisms of mechanically milled Al5083 alloy and Al5083−5wt.%B4C composite at room temperature and 200°C were discussed.Results revealed that due to the oxidative wear at room tem...Tribological behavior and wear mechanisms of mechanically milled Al5083 alloy and Al5083−5wt.%B4C composite at room temperature and 200°C were discussed.Results revealed that due to the oxidative wear at room temperature,a mechanically mixed layer(MML)was formed to protect the surface of the samples.Under 80 N of load at room temperature,the milled Al5083 and the Al5083−5wt.%B4C samples showed evidence of abrasion with limited volume loss.In this case,the wear rates were 5.8×10−7 and 4.4×10−7 mm3/(m·N),respectively.At 200°C and under 80 N of applied load,severe wear occurred in the milled Al5083 sample,and wear rate reached 10.8×10−7 mm3/(m·N)while the Al5083−5wt.%B4C sample showed mild wear with local 3-body abrasion and the wear rate reached 5.3×10−7 mm3/(m·N).Strengthening mechanisms such as dislocation pinning and the Hall−Petch theory,high hardness and the load transfer effect were crucial in determining the wear behavior of the Al5083−5wt.%B4C composite.On the other hand,the milled Al5083 sample represented a relatively high wear rate at 200°C,which seemed to be related to the local grain growth and a drop in its hardness.展开更多
Microstructural characteristics and mechanical behavior of hot extruded Al5083/B4C nanocomposites were studied.Al5083and Al5083/B4C powders were milled for50h under argon atmosphere in attrition mill with rotational s...Microstructural characteristics and mechanical behavior of hot extruded Al5083/B4C nanocomposites were studied.Al5083and Al5083/B4C powders were milled for50h under argon atmosphere in attrition mill with rotational speed of400r/min.For increasing the elongation,milled powders were mixed with30%and50%unmilled aluminum powder(mass fraction)with meanparticle size of>100μm and<100μm and then consolidated by hot pressing and hot extrusion with9:1extrusion ratio.Hot extrudedsamples were studied by optical microscopy,scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),transmission electron microscopy(TEM),tensile and hardness tests.The results showed that mechanical milling process andpresence of B4C particles increase the yield strength of Al5083alloy from130to566MPa but strongly decrease elongation(from11.3%to0.49%).Adding<100μm unmilled particles enhanced the ductility and reduced tensile strength and hardness,but usingthe>100μm unmilled particles reduced the tensile strength and ductility at the same time.By increasing the content of unmilledparticles failure mechanism changed from brittle to ductile.展开更多
Background and aim: Instability in the hemodynamic symptoms has been common at the time of extubation in patients and the cause to create the side effects. The aim of this research was to study the effect of injection...Background and aim: Instability in the hemodynamic symptoms has been common at the time of extubation in patients and the cause to create the side effects. The aim of this research was to study the effect of injection of Alfentanil, Lidocaine and their composition in reduction of side effects arising from extubation. Materials and methods: 172 patients (20 - 40 years old) that referred to Shahid Rajaee Hospital in 2014 and had been under the orthopedic surgery, were divided randomly and by using colored cards into four equal groups (43 patients in each group). Alfentanil (5 microgram/kilogram) was injected to the first group. The second group received Lidocaine (1 milligram/ kilogram). The composition of these two drugs was injected to the third group and the normal equal volume of Saline was injected to the fourth group which was the control group. The means of systolic and diastolic blood pressure, average arterial pressure and the number of heartbeat at the time of extubation were measured and registered 1, 5, 10, 15 and 20 minutes after extubation. Also, the amount of situation of bucking after extubation was registered in the groups. Results: The demographic results were similar in all groups. The mean of systolic blood pressure and number of heartbeats in the group of Alfentanil and composition of Alfentanil-Lidocaine had significant reduction (p 0.05). The situation of bucking in three treatment groups had significant reduction in comparison with control group. Conclusion: Alfentanil and composition of it with Lidocaine both had caused reducing the systolic blood pressure and heartbeats.展开更多
Advanced management algorithms are required in modern power systems to sustain energy supply with the highest availability and lowest cost.These algorithms need to be capable of not only maintaining scalability,tracta...Advanced management algorithms are required in modern power systems to sustain energy supply with the highest availability and lowest cost.These algorithms need to be capable of not only maintaining scalability,tractability,and privacy,but also enabling the utilization of grid-edge aggregated flexibilities in transmission systems.This paper proposes a distributed hierarchical transactive energy management(TEM)scheme to manage peak load and line congestion problems using connected and aggregated flexibilities.In the scheme,resource owners can privately solve their respective preference problems and send their scheduled power to the corresponding node operator(NO).Afterward,NOs solve a coordination problem to harmonize the actions of resource owners at the same node.Meanwhile,the independent system operator(ISO)updates control signals to steer the scheduled power to a feasible and optimal point.To accomplish all these,a hybrid decomposition approach is further proposed based on consensus+exchange alternating direction method of multipliers(CE-ADMM)and dual decomposition(DD)(CE-ADMM+DD).Besides,a dynamically constrained cutting plane(DC-CP)update algorithm is evolved to control the feasibility condition and minimize sensitivity to initialization.The proposed hybrid decomposition approach is verified and its performance is compared with other reported approaches.Application to various networks verifies its scalability,enhanced accuracy,and convergence speed.展开更多
Like many other ancient cultures,China possesses an impressive and celebrated literary heritage. The master poets of the medieval Tang Dynasty(618-907), for example, are rightfully known as some of the world’s best l...Like many other ancient cultures,China possesses an impressive and celebrated literary heritage. The master poets of the medieval Tang Dynasty(618-907), for example, are rightfully known as some of the world’s best lyric poets; the adventures of the Monkey King and his company—as told in the classical Chinese narrative Journey to the West—have achieved a global following (in part due to TV adaptations and the like); and novels, short story collections and memoirs by expat Chinese authors living in the West have won major literary prizes and become international bestsellers.展开更多
基金Authors would like to appreciate the former chief of Faculty of Materials&Manufacturing Processes of the Malek-Ashtar University of Technology,Professor EHSANI and the chief of the Composite Department,Dr.POURHOSSEINI along with the Razi and Kimiazi SEM labs and mechanical properties and SEM labs of Iran University of Science and Technology.Furthermore,the authors would like to thank Professor REZAEI,Ms.HAMIDI,and Ms.DAYYANI,Mr.SA'ADAT,and Mr.ATAEI from Iran University of Science and Technology.Special thanks to Mrs.KESHAVARZ,Ms.HAMEDANIZADEH,Ms.SHABANI,Ms.SHOJAEI and Mr.GANDOMKAR for their help and support.
文摘Tribological behavior and wear mechanisms of mechanically milled Al5083 alloy and Al5083−5wt.%B4C composite at room temperature and 200°C were discussed.Results revealed that due to the oxidative wear at room temperature,a mechanically mixed layer(MML)was formed to protect the surface of the samples.Under 80 N of load at room temperature,the milled Al5083 and the Al5083−5wt.%B4C samples showed evidence of abrasion with limited volume loss.In this case,the wear rates were 5.8×10−7 and 4.4×10−7 mm3/(m·N),respectively.At 200°C and under 80 N of applied load,severe wear occurred in the milled Al5083 sample,and wear rate reached 10.8×10−7 mm3/(m·N)while the Al5083−5wt.%B4C sample showed mild wear with local 3-body abrasion and the wear rate reached 5.3×10−7 mm3/(m·N).Strengthening mechanisms such as dislocation pinning and the Hall−Petch theory,high hardness and the load transfer effect were crucial in determining the wear behavior of the Al5083−5wt.%B4C composite.On the other hand,the milled Al5083 sample represented a relatively high wear rate at 200°C,which seemed to be related to the local grain growth and a drop in its hardness.
文摘Microstructural characteristics and mechanical behavior of hot extruded Al5083/B4C nanocomposites were studied.Al5083and Al5083/B4C powders were milled for50h under argon atmosphere in attrition mill with rotational speed of400r/min.For increasing the elongation,milled powders were mixed with30%and50%unmilled aluminum powder(mass fraction)with meanparticle size of>100μm and<100μm and then consolidated by hot pressing and hot extrusion with9:1extrusion ratio.Hot extrudedsamples were studied by optical microscopy,scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),transmission electron microscopy(TEM),tensile and hardness tests.The results showed that mechanical milling process andpresence of B4C particles increase the yield strength of Al5083alloy from130to566MPa but strongly decrease elongation(from11.3%to0.49%).Adding<100μm unmilled particles enhanced the ductility and reduced tensile strength and hardness,but usingthe>100μm unmilled particles reduced the tensile strength and ductility at the same time.By increasing the content of unmilledparticles failure mechanism changed from brittle to ductile.
文摘Background and aim: Instability in the hemodynamic symptoms has been common at the time of extubation in patients and the cause to create the side effects. The aim of this research was to study the effect of injection of Alfentanil, Lidocaine and their composition in reduction of side effects arising from extubation. Materials and methods: 172 patients (20 - 40 years old) that referred to Shahid Rajaee Hospital in 2014 and had been under the orthopedic surgery, were divided randomly and by using colored cards into four equal groups (43 patients in each group). Alfentanil (5 microgram/kilogram) was injected to the first group. The second group received Lidocaine (1 milligram/ kilogram). The composition of these two drugs was injected to the third group and the normal equal volume of Saline was injected to the fourth group which was the control group. The means of systolic and diastolic blood pressure, average arterial pressure and the number of heartbeat at the time of extubation were measured and registered 1, 5, 10, 15 and 20 minutes after extubation. Also, the amount of situation of bucking after extubation was registered in the groups. Results: The demographic results were similar in all groups. The mean of systolic blood pressure and number of heartbeats in the group of Alfentanil and composition of Alfentanil-Lidocaine had significant reduction (p 0.05). The situation of bucking in three treatment groups had significant reduction in comparison with control group. Conclusion: Alfentanil and composition of it with Lidocaine both had caused reducing the systolic blood pressure and heartbeats.
基金supported by the National Sciences and Engineering Council of Canada(NSERC)(No.Alliance-ALLRP 567550-21)Innovation en Ener-gie Electrique(Innovéé),Québec,Canada(No.PSO-2101)。
文摘Advanced management algorithms are required in modern power systems to sustain energy supply with the highest availability and lowest cost.These algorithms need to be capable of not only maintaining scalability,tractability,and privacy,but also enabling the utilization of grid-edge aggregated flexibilities in transmission systems.This paper proposes a distributed hierarchical transactive energy management(TEM)scheme to manage peak load and line congestion problems using connected and aggregated flexibilities.In the scheme,resource owners can privately solve their respective preference problems and send their scheduled power to the corresponding node operator(NO).Afterward,NOs solve a coordination problem to harmonize the actions of resource owners at the same node.Meanwhile,the independent system operator(ISO)updates control signals to steer the scheduled power to a feasible and optimal point.To accomplish all these,a hybrid decomposition approach is further proposed based on consensus+exchange alternating direction method of multipliers(CE-ADMM)and dual decomposition(DD)(CE-ADMM+DD).Besides,a dynamically constrained cutting plane(DC-CP)update algorithm is evolved to control the feasibility condition and minimize sensitivity to initialization.The proposed hybrid decomposition approach is verified and its performance is compared with other reported approaches.Application to various networks verifies its scalability,enhanced accuracy,and convergence speed.
文摘Like many other ancient cultures,China possesses an impressive and celebrated literary heritage. The master poets of the medieval Tang Dynasty(618-907), for example, are rightfully known as some of the world’s best lyric poets; the adventures of the Monkey King and his company—as told in the classical Chinese narrative Journey to the West—have achieved a global following (in part due to TV adaptations and the like); and novels, short story collections and memoirs by expat Chinese authors living in the West have won major literary prizes and become international bestsellers.
